1. Field of the Invention
This invention comprises an information input/output system, driven by a printed circuit board on which numerous switching elements are integrated to individually correspond to associated picture elements arranged in a matrix (so-called "active matrix drive"); more specifically, a liquid crystal input/output system which allows information input via a light pen.
2. Description of the Prior Art
As a result of the recent trend toward office and laboratory automation, demand has steadily increased for input/output systems which act as man-machine interfaces in information exchange between man and labor-saving machines. Various kinds of display units such as LCD, CRT, LED, EL, PDP and VFD are used to relay information from the machines. On the other hand, keyboards, touch panels, graphic tablets, voice, etc. are employed as means of inputting characters and graphics, etc., According to the intended purpose. In addition to these means, which are classified as unilateral, the light pen has been put into practical application as a bilateral means of transmiting information; it consists of a photo-electric translation element called a "light pen" and a CRT (Braun tube). When the light pen is brought close to the CRT screen, beams from the CRT scan the position of the pen, the photo-electric translation element in the pen detecting the light and outputting the corresponding pulse. By comparing the timing of this pulse and that of the corresponding detection signal from the CRT, the position of the light pen can be determined. This method offers the advantages of ease in graphic input and simplicity of operation on the interactive method, which can be performed by persons not well trained in keyboard operation. However, it poses shortcomings such as higher power consumption, greater depth of unit and image warping, etc., problems inherent in CRT'S.